Loud-speaking telephone



ou. 27,1925. A 1,558,881

' M. C. lHOPKINS l LOUD SPEAKING TELEPHONE Filled May 9'1924' 2Sheets-Sheet 1 I '1 l g Y I A /0 i 9 f3 7a l 5 7 A )T b 4( f5 I l \l l'A I L;

il. a f I. a l L l f1 I C Y y g f e l s ,Q /6z y A' /4 h] li lllllllllZi 1925i 1,558,881`

M. C. HOPKINS LoUD SFEAKING TELEPHONE Filed May 9 1924 2 Sheets-Shut 2INVENTOR 5 lniprovements 15 a telephone reeeivm instrument an( :soreceiving instruments.

atented Oct. 27, 1925.,

nutren STATES 1,558,881 PATENT oFF'IcE. l

MARCUSC. HOPKINS, OE WASEZVNGTON, DISTRICT OF COLUMBIA, ASSIGNOB, BYDIRECT AND MESNE ASSIGNMENTS, TO HOPKINS CORPORATION, A CORPORATION OFDELA- WARE.

Application led May 9,

To all whomzzf m11 concern:

Be it known that I, Marions C. llornixs, residing at 1ilVashington,District ot' Columbia, havenvented-cetain new and useful inLoud-Speaking Telephones; and Ido hereby declare the following to be afull, clear, and exact descriptlon of the invention, such as will enableothers skilled in the art to which it appertains to io make and use thesaine.

This invention has to do with telephone receivinginstruments and moreparticularly instruments ot the loud speaking type.

The invention Ahas'or its object to rofluce particularly a loud spes ingtelephone 1nstrument, characterized by increased'etiiciency and improvedquality-of reproduction.

It is a matter of common knowledge that ce the cilciency ofordinaryntelephone receiving instruments is very'low, and hence that thevolume of sound produced by such instruments is small as compared withthe elecn trical energy required to operate them. In

:5 line, with the obg'ect ot obtaining increased efficiency theinvention is directed toward decreasing as mach as possible certain ofthe electrical or magnetic losses which account for the low etticiencyof ordinary telephone The invention contemplates a magnetic ltelephonestructure having' a diaphragm pivotally supported on an annular fulcrumconcentric therewith and ot smaller diameter than the dia- :.5 phragm; apermanent magnetic field acting ou the diaphragm both inside and outsidethe annular fulcrum so as to give the diaphragm a substantially balancedbias; and an electromagrnctic field energizablc in ae- Vio cordance withelectrical signaling iml'iulscs and arranged so as to actuate thediaphragm inside and outside the annular fulcrum altcrnately. Thestructural and electrical arrangement thus defined provides what 4.3amounts to a pushpuli actuation of the diaphragm and results. not onlyin markedly increasedA oliiciency. but in materially improvedquality-ol' reproduction.,

n addition to the novel feature of con.-

o struction referred to above, a` further feaef the back et thediaphragm to the open air.

/ :Loon-SPEAKING TELEPHoNE.

1924. Serial N'o. 712,012.

Still another feature ofthe invention consists in the provision .ofpermanent magnets ot' helical torni, by which arrangement the permanentmagnetic elements can be made of the desired length-thus securing,r thenecessary magnetic potcntials-but at the Same time keeping the size ofthe structure within reasonable limits.

`Other features reside in the details of construction. which can be more'readily brought out in the description which follows:

With reference to the accompanying drawing:

Fig. l is a vertical cross-section of a loud speaking telephoneinstrument representing onel ot' the preferred embodiments of' theinvention,

Fig. 2 is an elevational View correspondiner to Fig. l,

Fig. 3 is a horizontal cross-section along the lines 3-.-3 ot' Fig. 1,and

Fig. 4 is a horizontal cross-section along the line 4 4 of Fig. l

A pressed or spun, iron7 or soft steel member l and an annular member 2of the same material are assembled together and form, in combination, achannel in which is seated a ring winding 3 which isthe actuatingwinding of the device; A

A ring 4 preferably of hard rubber or some other suitable non-metallicsubstance is supporter1 on +he winding 3 and positioned concentricallywith respect thereto. Thering; 4: is formed with a pointed annularprojection on which is supported a magnetic diaphragm 5. lVth the ring 4properly positioned, a suitable filler of self-hardening substance suchas beeswax, or one of the well known insulating compounds, is pouredintothechannel. Upon hardening, this filler serves to hol-d the windingand ring 4 in place.

The portion of the structure abovethe diaphragm comprises a circularplate 6 preferbaly of iron or soft steel, a ring 7 of the same materialattached to the plate 6 by' mcans'ot' round head screws S anda throatmember 9 which may be conveniently made of brass. The ring 7 ischanneled at 7- to form a recess in which is seated a strip of softrubber tubing 10. The tubing l() bears against the diaphragm 5 inopposition to the ham its

pcash-1m;

Csm

. snppm "-2 of suffi-,mut vngth to miem fmge l WSH @have w surface Cf Hwconceal the magneticarsi'l, and generally improve the appgaragucefof thedevice.

Thetyp'e otwinding used vvin the strueture herein described isparticularly' desir able in that it permits cfa very large' 'numher ofampere' turns ata comparatively low ohmic resistance, thereby materiallyreducing resistance losses and consequently inenI TCD

"sii

creasing the eiiiciency of the instrument.`

ln an instrument substantially as disclosed herein, which has beenconstructed and successfully operated, the diaphragmv is of siliconsteel, 3 inches in diameter, .015 inch thick; the diameter of theannular fulcrum is 213g inches; the diameter oi the opening at f is.131% inches; the diameter of t e opening at g is 12,35 inches; theair-gaps are each approximately .010 inch; members l and 2 are each'madeoi cold rolled steel inch thick; and the winding 3 consists cfl turns ofNo. 33 enameled copper wire.

y For che purpose of preventing losses due to eddy currents, members land 2 are preferabiy slotted through as indicated at in Fig. 4.

This invention is capable of embodiment in many difiere-nt formsaud'should not be yconstrued as limited except as indicated by thesubjoined claims:

l claim:

l, ln atele'phone instrument, means for maintaining e continuousmagnetic field, a. diaphragm therein, 'supporting means `for saiddiaphragm, theperipheral portion of said diaphragm extending beyond saidsupporting means,'and 4magnetic means operable to actuate the peripheralportion of 'said diaphragm.

2. ln a elephone instrument, a diaphragm, supporting means for saiddiaphragm, the peripheral portion ot said die phragm extending beyondsaid supporting means, and magnetic means operable on said diaphragm atpoints thereon both inside and outside said supporting means tomagnetically actuate both the peripheral p0rtion and the center portionof 'said diaphragm.

3. lin a telephone instrument, a diaphragm,/siipporti1ig meanscomprising an annular member on which said diaphragm is supported,'theperipheral portion of said diaphragm extending beyond said annular'member, and actuating means adapted to act upon said diaphragm at pointsof ap'- plication thereon both inside and outside the area', thereofencompassed by said annular meinber,

lifn a telephone instrument, a lldiaphragm, an annular 'support-ingmember for said diaphragm, Asaid supporting member 'being mi smallerdiameter than said diaphra n, and electromagnetic means for actuaifingsaid diaphragm, sind electromagnetic means being adapted to actmagnetically upon said diaphragm at points thereon both inside andoutside the area thereof eu- ?)ompassed by said annular supporting mem-In a telephone instrument, a diaphragm, an annular supporting member forsaid diaphragm, said supporting member being ot' smaller diameter thansaid diaphragm, a permanent magnetic fie-ld having parallel ux path-sthrough the portions of said diaphragm inside and outside the areathereof encompassed by said annu r supporting member respectively, and-electromagnetic means operable in response to current im ressed thereonto increase the mag netic ux assing through one of sald parallel pat iswhile vdecreasing themagnetic flux passing through the other of saidparallel paths f and vice versa depending upon the direction ofimpressed current.

6. In a telephone instrument, a diaphragm, an annular supporting memberfor said diaphragm, said supporting member' being of smaller diameterthan said diaphragm, a pair of annular magnetic poles, one of seidlesgbeing Yadjacent the p'orticn of said diap ra within the areaencompassed by sail su p`ortin member, the other of said oies ing ajacent the portion of said riaphragm outsidesaid area, meahs foropposltely and variably energiz ing said poles inaccordance withcorrespondingly variable currents, whereby said diaphragm is actuated,andn means for impressing a. continuous magnetic potential of the samepolarity on each'of said poles.

7. In atelephone instrument,adiaphra m, an annular fulcruin, on which4said phragm is supported, the diameter oi said fulcrum beingsubstantially less. than the diameter of said diaphragm, resilient meansfor holding said diaphragm against said fulcrum, and electro-magneticmeans operable to act magneticallyon said diaphragm at points inside andoutside the area encompassedvby said annular fulerum,

8. In uitelephone instrument, a diaphragm,

an annular fulcrum on which said phragm is supported, the diameter-.ofsaid t ulorum bein substantially less than the dif ameter of saidiaphragm, an annular chanv nel of magnetic material, Van electro-magnety coil supported in said channel, the extremi ties of said channelformingumagnetic poles, one of which is disposed closel adjacent theportion of said. diaphragm within the areaencompassed by said annularvulcrum, the other of said poles being disposed closely adjacent theportion of said diaphragm outside said area, the magnetic potentials ofsaid poles caused by said coil being of opposite polarity, and means forimpressing a continuous magnet-ic potential of the'same polarity on eachof said poles.

iin e 'elephone instrumen, n. diaphragm, en annuler supper-ning memberfor Saki. die'- phrsggin seid snpporing member being of smeieidiurnes/e5;- than said diaphragm, ineens or producing e continuousmagnetic s: means having opposite magnetic cl, oserl respectively onopposite sides ci i? nphregm., and adizicen/ thereto, one esi( polesbeing hiurcned, the branches i ,ii oi-furciiteil pole being disposed MLscent seni diephrngm at points 'wihin Athe aree, hereo encompassed bysaid supporting member and. outside said oren respectiveiy, and aneiecronmgnet for actuating seid diaphragm, the branches of said hiHurceled pcie forming opposite poles of said electrom insignesrespec'ivelv.

l0. in 1 eleplione instrument, e diaphragm, en annuler ulcrunisupporting said diaphragm., said nlcrmnh being of smaller diameter "thansaid dinphregnn means lfor producing e continuons magnetic field, saidineens having epposiie simgnezic poles of nnnnisr form disposedrespecirely on opposie sides o1? seid diaphragm and adjacent thereto,thet one of seid poies which is on che. opposite side of sniiiiinphrngnifrom ulcrnni being disposed suhstaniniiy opposie said nlcrnni.,resilient means interposecl hein/een seicilast men'ioned pole und saisiahr-ogm emi hearing against seid {iiephragrn in oppesiion to saiduicrum, lie other of seid. poles heing hi-'furcaerh the branches of,seid hifnreaceei pcie being dis pwed mijncent #diaphragm ai' pointswithin he area ih reef encompassed hy said ifnicrnni inni ouiside saidaren resoeciively,

and :in eieerro-megne coi disposed heatn'een rthe 'branches olif .seidiii-forested pole, the extremities of the branches of said iii-furentecipole forming opposite 'poles of the elecromagnetic ield of said coil,said coil being opcrahle upon energization to efi'ect actuation of seiddiaphragm.

l1. In a teiephone insrument, a diaphragm, means for producing acontinuous ma fnetic eid for said die hm n1 saidV ineens comprising s,permanently magnetized thereof alternaely.

'14. The .method c operating a sound producing diaphragm which consistsin applying u plurality of continuous magnetic ab trncting' forces tothe diaphragm in physical opposition und ai substantially different(lisances' from he center of the diaphragm, und super-imposingiuctuating magnetic forces on said continuous magnetic forces in suchnmnner that ehe resultant forces up plied ro the diaphragm are' alteredin dierent degrees thereby causing sound producing rlisp'ecernens of thediaphragm. Y

En testimony whereof ax rnk signature.

MARQUE C. Hf FKNS.

Cil

